Xavier Davis, 28, was arrested Thursday in an unrelated family violence charge, authorities said.
Davis is accused of shooting Harmony Carhee, 6, and her parents, Donyavia Lagway and Gregory Carhee, in their Fondren Road apartment Wednesday night. Harmony's 10 year-old sister was also shot, but she played dead during the rampage before using FaceTime to call her grandmother.
READ ORIGINAL STORY: 'Brave' 10-year-old played dead, called grandma after family killed
'Brave' 10-year-old played dead, called grandma after family killed
"She was strong. She was hurt. But my baby came out of nowhere, from whatever way she had, to make stuff happen," grandmother Manda Lagway said earlier this week. "I just want everyone to know my baby is a hero. My baby is a hero."
The 10-year-old was released from the hospital on Friday, and is recovering from her injuries. She told police the man believed to be Davis knocked on the door of the apartment before the rampage.
He had a mask on and grabbed her 1-year-old baby brother by the hair and threw him, the little girl told police. He then shot the victims in the head.
She said she played dead and when the killer left, she got her brother and locked the door.
"Their lives have been permanently changed," said Houston mayor Sylvester Turner. "I just want to extend my condolences and prayers to these families whose lives have been changed in the last 48 hours."
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The 1-year-old was not injured, family said. The couple also has an 8-year-old son who was spending the night with his uncle the night of the shooting.
Suspect in custody in connection with family murdered